the fbi has opened an investigation into the deaths of ambassador stevens and the three other americans killed. at the state department, danielle nottingham, derek, back to you. >> thank you. of course, this is a reminder. there are thousands upon thousands of u.s. diplomats working overseas and this horrible killing incident is a reminder that this can be dangerous work. we should also note that many of them have studied, lived or worked right here in the d.c. area and bruce johnson is here with a story of how some of them are reacting to the slayings of the ambassadors and the others overseas. >> absolutely. they're saying it's dangerous work but they're surprised because after all, we supported the overthrow of gadhafi. the flag is at half staff outside the johns hopkins graduate school of advanced international studies in washington. >> we're often grateful to our military. we often forget the civilians who serve abroad. >> reporter: daniel serwer is a proffer of conflict resolution at hopkins. he's been in afghanistan, the balkans, iraq, the sudan and libya twice since the revoluti